This section provides background information related to the present disclosure which is not necessarily prior art.
Carbon aerogels are porous solids with interconnected carbon particles and so they exhibit high surface area and good electrical conductivity. Activated carbon aerogels are useful electrode materials for applications such as capacitive deionization, flow batteries, supercapacitors (or electric double-layer capacitors), and others. For example, interest in capacitive deionization systems, and making such systems more efficient, is growing in part because of growing interest in the use of deionization systems in desalination applications to remove salt from salt water. However, optimizing electrode design, for example the pore geometries of the electrode material to achieve improved efficiencies, still remains a challenge.
Additional information on the present state of the art involving three dimensional printing of aerogels may be found at the following: High surface area carbon aerogel monoliths with hierarchical porosity—Journal of Non-Crystalline Solids—354 (29), 2008, Proceedings of the National Academy of Sciences—111 (7), 2014, 3513-3515; Capacitive desalination with flow-through electrode—Energy and Environmental Science—5 (11), 2012, 9511-9519; Highly compressible 3D periodic graphene aerogel micro-lattices—Nature Communications—6 (6962), 2015; T. Baumann et al., reported a synthetically tailored high surface area (3000 m2/g) carbon aerogels with bimodal porosity which can be used as electrodes for electrochemical devices; M. Stadermann et al., described a model capacitive desalination (CD) cell which employed activated carbon aerogels as electrodes, with the efficiency of the cell being four times higher than a typical CD cell; Cheng et al., employed direct ink writing technique to prepare graphene aerogels with defined geometries.
3-D printing inks thickened with graphene oxide have also been made containing base catalyzed resorcinol-formaldehyde resins. Drawbacks from using such inks have been identified in the current work and represent further challenges in producing carbon aerogels downstream from the 3-D parts printed using the ink.